Hot tapping and line stopping machines are vitally
important tools across the upstream and downstream
oil and gas sector, as they allow repairs, tie-ins and plant
expansions to be made without interrupting supply to the
plant, and ultimately the customer.
The ability to complete pipeline repair in a timely
manner depends on availability of the right equipment for
the job – and the ongoing assurance that those machines
have been properly maintained.
A practical solution to addressing damage
risk
Hot tapping is often used to make repairs where corrosion
or other types of physical damage have occurred to
pipelines, although it can also be used in modifications or
upgrades to add branches to an existing network.
The ability to make these changes without reducing
pressure, venting pipelines and pressurised systems means
that not only is operational service uninterrupted, but
environmental concerns can be addressed.
There are some situations where hot tapping is
impractical or dangerous. The risk of burn-through,
unstable decomposition of the flowing product and
hydrogen cracking are all possible complications.
Without the use of hot tapping, production would
have to be shut down to expand the pipe network;
bringing all the commercial and environmental impact that
would accompany it. This makes the process a particularly
valuable one where it is possible to implement.
Continuous system operation
Plant shutdowns can be lengthy, expensive procedures –
maintaining operations while completing maintenance,
remedial or infrastructure alteration works will always be
the preferred option.
Hot tapping allows projects such as corrosion repair
or pipeline branch extensions to be completed without a
system shutdown being required.
The hot tapping process allows engineers to work on
live pipelines without leakage – reducing environmental
impact risk and ensuring production schedules are not
affected.
Adding a new branch and valve to an existing pipeline
using the hot tapping process is a relatively simple task
– fittings are usually welded in place and then valves,
adapters and the hot tapping machine will connect
through the valve and drill out a coupon. The valve is then
closed, the hot tapping machine removed and the branch
line connected.
Compared to the alternatives that require a redesign
of the pipeline, the closing off of the system and then
cutting, aligning and re-welding of the pipeline sections,
hot tapping is a quick and low-impact process.
When there is no interruption to the core plant
functions of the upstream or downstream operation,
production processes can continue as normal. There is
no impact on the plant itself and as a result stakeholders
reliant on delivery of hydrocarbon resources can be
assured that supply will not be interrupted.
Availability of rental machinery
Project managers facing constraints in their capex budgets
must consider whether investing in a hot tapping machine
for a single project is economically advisable. Whether
the project requires a high pressure, subsea capable hot
tapping machine or a small manual feed hot tapping
machine for the utilities industry, Mirage Machines has
deployed fully serviced rental assets in the field.
Meeting subsea challenges
Mirage Machines’ CHT range, with a working pressure
capacity of up to 5000 psi, were specifically designed for
pipeline intervention and wellhead maintenance across the
oil and gas, petrochemicals and utilities sector.
The CHT range has been deployed for hot tapping
operations from 3 - 36 in. It was developed to include a
drive as close to the cut as possible to provide improved
cutting efficiency, auto feed to meet challenges in variable
pipelines and cutting conditions, and a geared mechanical
depth display to give engineers a greater level of control
whilst reducing the operating height/
length of the equipment.
It has been developed to meet
significant subsea demands with a
constant pressure seal monitoring port,
and an internal pressure-balanced system
for high pressure applications and
capability added for ROV deployment.
Addressing requirements in lower
pressure environments, Mirage developed
the MHT range with a 1480 psi operating
capacity and extended operating range
from 3 - 60 in. whilst maintaining as many
of the CHT proven features as possible,
while keeping the industry-familiar
operating procedures for the technician.
Figure 2.
A hot tapping machine with a working pressure capacity of 5000 psi
maximum.
72
World Pipelines
/
JUNE 2015
